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目的对接受功能影像引导动态调强放疗的鼻咽癌患者进行治疗前的剂量学验证,初步探索功能影像引导调强放疗的可行性。方法选取11例接受功能影像引导放疗的Ⅰ~ⅣA期鼻咽癌患者进行治疗前的绝对剂量和相对剂量的验证。采用不同的显像技术(CT、~(18)F-氟代脱氧葡萄糖PET/CT)指导鼻咽癌靶区的勾画与治疗计划的制定,利用Varian 23EX加速器、电离室、I’mRT MatriXX二维电离室矩阵、IBA可拆装体模在治疗前进行绝对剂量与相对剂量验证。结果感兴趣区域的绝对剂量相对误差取值在-5.80%~5.23%(2.39±0.66)%。采用差热分析法,剂量限定在3%或3mm标准条件下,采用300MU/min测量时通过的野数占总野数的87.64%。使用300MU/min测量的gamma通过率高于使用500MU/min测量的gamma通过率(P<0.01)。结论剂量学验证是调强放疗质量控制的必要步骤。使用电离室和I’mRT MatriXX二维电离室矩阵及相应的验证软件可以对鼻咽癌原发灶高代谢区进行剂量学验证,并初步证明功能影像引导动态调强放疗是可行的。
Objective To evaluate the dosimetry of patients with nasopharyngeal carcinoma who underwent dynamic intensity modulated radiotherapy guided by functional imaging and to explore the feasibility of functional image-guided intensity modulated radiotherapy. Methods Eleven patients with stage Ⅰ-ⅣA nasopharyngeal carcinoma undergoing functional radiotherapy guided radiotherapy were enrolled in the study. The absolute and relative dosages were determined before treatment. Different visualization techniques (CT, ~ (18) F-fluorodeoxyglucose PET / CT) were used to guide the delineation and treatment planning of nasopharyngeal carcinoma target. Varian 23EX accelerator, ionization chamber, I’mRT MatriXX Dimensional ionization chamber matrix, IBA removable phantom in the treatment of absolute dose and relative dose verification. Results The relative error of absolute dose in the region of interest ranged from -5.80% to 5.23% (2.39 ± 0.66)%. Using differential thermal analysis, the dose limited to 3% or 3mm standard conditions, the use of 300MU / min measured when the number of wild-type 87.64% of the total number of fields. The gamma passage rate measured using 300 MU / min was higher than the gamma passage rate measured using 500 MU / min (P <0.01). Conclusion Dosimetry verification is a necessary step in the quality control of IMRT. Using the ionization chamber and the I’mRT MatriXX two-dimensional ionization chamber matrix and the corresponding verification software, we can perform dosimetry verification on the high metabolism area of the primary tumor of nasopharyngeal carcinoma, and preliminarily prove that functional image-guided dynamic intensity modulated radiotherapy is feasible.